The latest trend in urban design is blurring the line between civilization and nature to create parks from contaminated sites, landfills, and abandoned manufacturing plants.  Former brownfields like a 9-acre parcel of land on Puget Sound, once dotted with UNOCAL’s oil tanks, is now home to Seattle’s spanking new Olympic Sculpture Park.  Landscape architects are also tackling awkward space that is no longer viable.  Take, for example, High Line Park, open last week on the West Side of Manhattan.  For decades, the High Line served as an elevated railway track that brought freight into the city.  By 1980, the trains had stopped running and the tracks were sliding into decay that, somewhat remarkable, was also a kind of blossoming.  Nature re-established itself as saplings and wind-sown grasses sprouted in the rail beds.  The trees took root and so did an inkling of an idea, almost Seuss-like, to create a public space that would be 30-feet high above the city and nearly 1.5 miles long.  That fantasy has thankfully come to fruition. www.thehighline.org